Field of the Invention
The present disclosure relates to a method for controlling an inverter.
Description of Related Art
Generally, when a pump is directly started for pump control, chances are that an excessive pressure is instantly applied to a pump pipe to damage the pump or a pipe connecting the pump to a water tank may be damaged.
In order to solve the aforementioned problem, a normal acceleration/deceleration is performed to a pre-PID (Proportional Integral Derivative) frequency, where a pre-PID delay time (so call “soft fill time”) is maintained. When a feedback relative to a pressure is less than a pre-PID exit set up by a user, a normal PID control is performed after lapse of the pre-PID. When the pressure reaches the pre-PID frequency, the PID control is not performed during maintenance of the pre-PID soft fill time.
FIGS. 1a and 1b are exemplary views illustrating a conventional inverter control, where FIG. 1a is an exemplary view illustrating a case where feedback has reached a pre-PID soft fill time value before lapse of the pre-PID soft fill time in the pre-PID frequency, and FIG. 1b illustrates a case where the feedback is less than a pre-PID soft fill value even after maintenance of the pre-PID soft fill time.
Referring to FIG. 1a, it can be noted that a normal PID is performed when pressure data returned before end of the pre-PID soft fill time in the pre-PID frequency reaches a pre-PID soft fill value.
However, as shown in FIG. 1b, in a case a pressure data returned even after lapse of the pre-PID soft fill time has many differences over the pre-PID soft fill value, PID control burden rate increases when a normal PID starts to suddenly increase a PID output, and as a result, a pump damage by changes in sudden pump pressure cannot be disadvantageously prevented.